Process of reducing metallic sulfids.



No. 862,871. PATENTED AUG.13, 1907.

E. L. ANDERSON.

PROCESS OPREDUCING METALLIC SULFIDS. APPLIOAT'ION FILED FEB. 23, 1901.

WITNESSES: INVEN TOR.

@ I Eduarzflflzdrsoiz ATTORNEY.

. present, as is usually' the case of copper ores. the iron able carbon.

UNITED STATES .PArENT OFFICE.

EDWARD L. ANDERSON, OF ST. LOUIS, MISSOURI, ASSIGNOR OF ONE-FOURTH TOTHOMAS B. HARVEY, OF ST. LOUIS; MISSOURI.

PROCESS OF REDUCINZG.METALLIC SULFIDS.

Specification of Letters Patent.

Patented Aug. 13, 1907-.

Application filed Pebrnary 23, 1907- Serial No. 358,946.

To all whom it may concern:

Be it known that I, EDWARD L. ANDERSON, a citi-.

sists in the novel series of steps more fully set forth in the specification and pointed out in the claims.

In the drawings, Figure 1 is a vertical transverse sec-,

tion on line 1-1 of Fig. 2 of the reduction tank; and Fig. 2 is a longitudinal vertical section on the line 22 I of Fig. 1 with part of the diaphragm broken away.

The object of my invention is to effect the electrolytic reduction of metallic sulfids, carbonates, oxids, and other compounds notably of copper and lead (though the process is not restricted to these metals). Incases where the ore or compound is initially a sulfid,- use is made of the nascent hydrogendisengaged from the electrolyte at the cathode which, acting upon the sulfur constituent of the ore, converts the same into sulfureted hydrogen, the elimination of the sulf 1r in the manner indicated leaving the metal behind the metallic state. By then reversing the current, the metal goes into solution in the electrolyte and is subsequently deposited from said solution on what now becomes the cathode end of the circuit. Where the ore 'or compound is a carbonate or oxid or any other compound capable of entering into initial solution in the; electrolyte, the passage of the current from the anode to the cathode at once causes the metal of .the solution to be deposited on the cathode.

,Various solutions and acids have been employed as the electrolyte, notably sulfuric acid which has the capacity of dissolving the majority of metallic comfids are dissolved by sulfuric acid; and where iron is completely, the carbon diffusing itself throughout the solution as to materially interfere with the deposition ,of the metal at the cathode; and the metal which does deposit is generally impregnated with the objection- For the foregoing reasons, sulfuric acid is not only not desirable but is objectionable. and I accordingly avoid it.

Ari important feature of my process is the selection and use of an electrolyte which, though fully capable of dissolving the metals to be recovered, shall have little affinity for ferric oxid and sulfid which so readily combine with sulfuric acid, and whose solution gives rise to the obj ections aoove referred to. Sulfids of iron and zinc do not reduce at the cathode under the action of nascent hydrogen (as above explained) and if present in copper and lead ores which do reduce and subsequently pass into solution, they (the iron and zinc sulfide) can be readily separated since they simply precipitate themselves in'an insoluble form to the bottom of the tank; and tothe extent that the iron may dissolve in the electrolyte entering into my process, it

will be converted at'the anode into a higher oxid' of iron practically insoluble in the electrolyte and likewise precipitate itself to the bottom of the tank. My

.electrolyte'therefore offers the advantage in that it does not disintegrate the anode to any material extent (an unavoidable consequence/with sulfate solutions), but it also has so slight an affinity for iron and zinc sulfids, and similar foreign metals not intended to be recovered, that it in no wise interferes with the electrodeposition of the metals sought (copper or lead). Where two ormore recoverable metals are present in the solution, they may be deposited independently and separately on thecathode by properly regulating the current density and working voltage by which their dissociation from the solution is effected. 'Ihe electrolyte employed in my process is silico-hydrofluoric (hydro-fluo-silicic) acid, H SiF and as anillustration of my process I will take copper sulfid as the ore to be treated.

Referring to thadrawings, 1 represents a wooden reduction tank of suitable shape and dimensions in which is contained an aqueous solution of the electrolyte E. Into this are inserted the electrodes 2, 2 of carbon or graphite one of said electrodes at the first stage of the process serving as an anode and the other as a primary cathode. being is the primary cathode is a perforated wooden plate or diaphragm 3, from which is suspended a linen or convas sheet or filter 4 which allows for the circula tion of the liquid, but intercepts the fine particles of the ore O packed between the primary cathode and the diaphragm The ore by its proximity to the primary cathode serves as an additional or secondary cathode, the secondary cathode being decomposable under the action of the current. Assuming that the ore is initially a sulfid of copper, and assuming that the current passes through the electrolyte from left to right, that is toward the ore and cathode along which the same is disposed, there will at once be a disengagement of nascent hydro- Disposed in proximity to what for the time gen- (from the water) at the cathode. The hydrogen immediately attacks the sulfur of the ore, formingsulfureted hydrogen gas which passes off, and if desirable may be conducted to any point of consumption. After a certain quantity of the sulfid is thus reduced, (the reduction resulting in metallic, copper at the cathode) the current is reversed, so as to pass from the ore to the opposite electrode, the cathode becoming the anode, and the anode becoming the' cathode. The plain arrow indicates the direction of the reducing or original current, and the ieathered arrow that of the electro-de-- positing current. Upon reversal of the current the metal previously reduced goes into solution (as a salt I and then the other until the total quantity of metal is reduced and recovered, the sheets'm being of course always peeled off previous to the conversion of the electrode to which the sheet adheres, into an anode.

Where the compound or ore is initially soluble in the electrolyte which is the case with carbonates or oxids, there will be no occasion in placing the ore in contact with the electrode serving initially as the oathode, as there is no sulfur to be got rid of and the ore can be dumped into the electrolyte and the current started in' either direction, the sheet meta l depositing on the cathode as already described. In some cases I may use hydro-fluoric acid to produce the soluble fluorid of the metal to be recovered Having described my invention what I claim is:

1, in the reduction of metallic suifids, the process of subjecting the sulfid to the action of an electric current flowing from an insoluble anode to a correspondingly insoluble cathode and to the sulfid, in an electrolyte capable of dissolving the metal constituent of the sulfid andformlng a salt therewith, ihen reversing the current whereby the salt is decomposed and the metal of said salt is deposited on the electrode which now becomes the cathode, substantially as set forth.

' 2. In the reduction of sulfid ores, the process of subjecting the ore to the action .of an electric current flowing from an insoluble anode to the ore serving as a cathode,

in anelectrolyte capable of dissolving the metal constituent of the ore when freed of its sulfur, thenreverslng the current whereby the salt solution thus formed is decomposed and-the metal becomes deposited on the resulting cathode, substantially as set forth.

ln thc reduction of sulfid ores, the process of subject ing the ore to the action of an electric current flowing from an insoluble anode to a primary insoluble cathode in the presence of a quantity of the ore serving as a secondary decomposable cathode, in an electrolyte capable of dissolving the metal constituent of said secondary cathode, then reversing the current whereby the solution of the salt of the metal-of the ore is decomposed and the metal is deposited on the electrode which becomes the cathode, substantially as set forth.

4, In the reduction of metallic compounds the process of first forming an aqueous solution of the salt resulting from the union of the metal constituent of the compound and silico hydro-fluorlc (hydro-fiuo-sillclc) acid then subjecting said salt solution to the action of an electric current flowing from an insoluble anode to a cathode immersed in said solution, whereby the metal is deposited on the cathode, substantially as set forth.

in testimony whereof I aflix my signature, in presence of two witnesses.

EDWARD L. 'ANDERSON.

Witnesses Ema Srannx, Jos. A. MICHEL. 

